The present invention is directed to exposure apparatuses. More specifically, the present invention is directed to a modular exposure apparatus and a method for making a modular exposure apparatus. Additionally, the present invention is directed to an exposure apparatus having improved isolation of the optical device.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes a support frame, a measurement system, a control system, an illumination source, an optical device, a reticle stage for retaining a reticle, and a wafer stage for retaining a semiconductor wafer.
The support frame typically supports the measurement system, the illumination source, the reticle stage, the optical device, and the wafer stage above the ground. The measurement system monitors the positions of the stages relative to a reference such as the optical device. The optical device projects and/or focuses the light that passes through the reticle. The reticle stage includes one or more movers to precisely position the reticle relative to the optical device. Similarly, the wafer stage includes one or more movers to precisely position the wafer relative to the optical device.
The size of the images and features within the images transferred onto he wafer from the reticle are extremely small. Accordingly, the precise positioning of the wafer and the reticle relative to the optical device is critical to the manufacture of high density, semiconductor wafers.
Unfortunately, mechanical vibrations and deformations in the support frame of the exposure apparatus can influence the accuracy of the exposure apparatus. For example, the movers utilized to move the stages generate reaction forces that vibrate and deform the support frame of the exposure apparatus.
The vibrations and deformations in the support frame can move the stages and the optical device out of precise relative alignment. Further, the vibrations and deformations in the support frame can cause the measurement system to improperly measure the positions of the stages relative to the optical device. Additionally, vibration of the optical device can cause deformations of lens elements within the optical device and degrade the optical imaging quality. As a result thereof, the accuracy of the exposure apparatus and the quality of the integrated circuits formed on the wafer can be compromised.
One attempt to solve this problem involves the use of a support frame having a main frame and a reaction frame. The main frame is used to support most of the components of the exposure apparatus above the ground, while the reaction frame is used to transfer the reaction forces from the motors of the stages to the ground. Unfortunately, with this design, the optical device and the measurement system may still be subjected to reaction forces and disturbances that can influence the accuracy of the exposure apparatus. Moreover, with this design, the assembly and disassembly of the exposure apparatus can be time consuming and difficult.
Further, the combination of the main frame and the reaction frame limits and restricts access to many of the components of the exposure apparatus. For example, with current designs, multiple components of the exposure apparatus must be removed to access the optical device. As a result thereof, service and adjustment of the optical device is very difficult and time consuming.
In light of the above, it is an object of the present invention to provide an exposure apparatus with improved isolation of the optical device and the measurement system. Another object is to provide an exposure apparatus with improved access to the optical device. Yet another object is to provide an exposure apparatus that is relatively easy to assemble and disassemble. Still another object is to provide an exposure apparatus capable of manufacturing precision devices, such as high density, semiconductor wafers.
The present invention is directed to an exposure apparatus for transferring an image onto a device, i.e. a semiconductor wafer that satisfies these needs. The exposure apparatus includes a base assembly, a base isolation system for securing the base assembly to the mounting base, an optical assembly, and an optical isolation system for securing the optical assembly to the base assembly. The base assembly includes at least a portion of a stage assembly and the optical assembly includes an optical device. The base isolation system reduces the effect of vibration of the mounting base causing vibration on the base assembly. Further, the optical isolation system reduces the effect of vibration of the base assembly causing vibration on the optical assembly.
Importantly, the base assembly is isolated from the mounting base with the base isolation system and the optical assembly is isolated from the base assembly with the optical isolation system. Hence, the assemblies are effectively attached in series to the mounting base with the isolation systems and the optical device is isolated from the mounting base with two levels of isolation systems. The two isolation systems better isolate the optical device from vibration and disturbances. This allows for more accurate positioning of the reticle and the semiconductor wafer relative to the optical device and the manufacture of higher quality and higher density semiconductor wafers.
Further, as provided herein, many of the components of the base assembly and many of the components of the optical assembly can be added to the exposure apparatus as a module. As a result of the modular design, the optical device and the other components of the optical assembly can be accessed relatively easily for service and adjustment. Additionally, the exposure apparatus can be assembled and disassembled easier. This minimizes downtime for the exposure apparatus.
As provided herein, the base isolation system can include a plurality of spaced apart base flexible supports for attenuating movement of the base assembly relative to the mounting base and a plurality of spaced apart base movers for adjusting the position of the base assembly relative to the mounting base. Similarly, the optical isolation system can include a plurality of spaced apart assembly flexible supports for attenuating movement of the optical assembly relative to the base assembly and a plurality of spaced apart assembly movers for adjusting the position of the optical assembly relative to the base assembly.
The base assembly can include a base frame that supports a portion of a first stage assembly and a second stage assembly. The base frame includes a base frame aperture that receives the optical assembly and the optical device.
The optical assembly can include an optical frame, the optical device, a portion of the measurement system, and a first stage base of the first stage assembly. The optical device is attached to the optical frame and the combination can be added to and removed from the exposure apparatus as a module. The first stage base is supported by the optical frame. The optical assembly concept provided herein allows the optical device and the optical frame to be removed as a module.
As provided herein, the exposure apparatus also includes a support frame that extends between the mounting base and the base isolation system. The support frame supports the base assembly above the mounting base.
The present invention is also directed to a method for making an exposure apparatus, a method for making a device, and a method for manufacturing a wafer.
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